Workload Characterization of Multithreaded Java Servers on Two PowerPC Processors

Java has, in recent years, become fairly popular as a platform for commercial servers. However, the behavior of Java server applications has not been studied extensively. We characterize two multithreaded Java server benchmarks, SPECjbb2000 and VolanoMark 2.1.2, on two IBM PowerPC architectures, the RS64-III and the POWER3-II, and compare them to more traditional workloads as represented by selected benchmarks from SPECint2000. We find that our Java server benchmarks have generally the same characteristics on both platforms: in particular, high instruction cache, ITLB, and BTAC (Branch Target Address Cache) miss rates. These benchmarks also exhibit high L2 miss rates due mostly to data loads. As one would expect, instruction cache and L2 misses are primary contributors to CPI. Also, the proportion of zero dispatch cycles is high, indicating the difficulty in exploiting ILP for these workloads.